The trigger menu handler of the ATLAS Level-1 Central Trigger Processor

The role of the Central Trigger Processor (CTP) in the ATLAS Level-1 trigger is to combine information from the calorimeter and muon trigger processors, as well as from other sources, e.g. calibration, and to make the final Level-1 decision. The information sent to the CTP consists of multiplicity values for a variety of (electron, gamma, tau/hadron and jet) transverse-momentum thresholds, and of flags for transverse-energy sum thresholds. The algorithm used by the CTP to combine the different trigger inputs allows events to be selected on the basis of menus. Different trigger menus have to be considered for different run conditions. In order to provide sufficient flexibility and to fulfil the required low latency, the CTP will be implemented with look-up tables and programmable logic devices. The trigger menu handler is the tool which translates the human-readable trigger menu into the configuration files necessary for the hardware. It stores several prepared configurations and down-loads them into the hardware on request. An automatic compiler of the trigger menu and a prototype of the trigger menu handler have been implemented.